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Discussion Starter · #1 ·
Hi could somebody please tell me where to find the thermal sensor that controls the two fans which are now always on no matter what?

Or could it be something else?
thanks
 

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Are the fans on even when the ignition switch is at Off? If so, then this could be a relay with a bad internal contact that is remaining closed. (If both fan motors are running, the sub-fan relay remaining closed could cause this. If the sub-fan relay is faulty, and is pulled out, both fans should stop.)

If the fans are not on with the switch at Off, but come on as soon as the switch is at On, do they run even when the instrument panel temperature gauge is below the normal position (~9:00 o'clock)? If they do run when the gauge is below normal, then the cause is not likely to be the engine coolant temperture sensor. In this case, what engine and transmission does your 2005 have? There was a recall issued back in 2007 relating to a faulty fan relay that could damage the ECM, and cause the fans to remain on. (See attached.)

If the fans run continuously, but only when the engine is also running, then check the HVAC controls. If the controls are set to either of the two windshield defrost positions and the HVAC fan control is not at Off, the AC can be running (even though AC hasn't actually been turned on) and when it does, the two radiator fans will usually be running as well.
 

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Discussion Starter · #3 ·
fan always on

Are the fans on even when the ignition switch is at Off? If so, then this could be a relay with a bad internal contact that is remaining closed. (If both fan motors are running, the sub-fan relay remaining closed could cause this. If the sub-fan relay is faulty, and is pulled out, both fans should stop.)

If the fans are not on with the switch at Off, but come on as soon as the switch is at On, do they run even when the instrument panel temperature gauge is below the normal position (~9:00 o'clock)? If they do run when the gauge is below normal, then the cause is not likely to be the engine coolant temperture sensor. In this case, what engine and transmission does your 2005 have? There was a recall issued back in 2007 relating to a faulty fan relay that could damage the ECM, and cause the fans to remain on. (See attached.)

If the fans run continuously, but only when the engine is also running, then check the HVAC controls. If the controls are set to either of the two windshield defrost positions and the HVAC fan control is not at Off, the AC can be running (even though AC hasn't actually been turned on) and when it does, the two radiator fans will usually be running as well.

Hi, thanks for the detailed reply. It's exactly as in your paragraph 2 - both fans are always on as soon as the switch goes on, even when completely cold. A/C compressor off. However, it's not a turbo (could use it) and so doesn't seem to fit the parameters of the recall notice? Should I check the relays anyway? Is there a procedure for that that you know of? I have meters. Thanks.
 

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Hi, thanks for the detailed reply. It's exactly as in your paragraph 2 - both fans are always on as soon as the switch goes on, even when completely cold. A/C compressor off. However, it's not a turbo (could use it) and so doesn't seem to fit the parameters of the recall notice? Should I check the relays anyway? Is there a procedure for that that you know of? I have meters. Thanks.
Relays can be checked for continuity through the energizing coil, and for continuity through the internal switching contacts when the relay is energized. There's three relays involved in the control of the two fan motors. According to the recall notice, one of the relays, main relay #2, was defective. On page 4 of the recall notice there's a photo of what the replacement relay looks like. Check to see if your relay has the same reference number and the gray dot.

I've attached a wiring diagram. Each of the three relays can be removed and tested for continuity through the energizing coil, and then with a 9V battery to energize the coil, the relay switching contacts can be checked for continuity. (Search Google -- there's web sites and YouTube videos explaining how to test automotive relays.) There's a diagram on the underside of the engine compartment main fuse box cover. The location of the three fan-related relays is indicated there. (The relays are held in place by tabs on the side. The tabs have to be released before the relays can be pulled up. Even when they are released, the relays can be difficult to pull out.)

But some simpler tests might help focus the troubleshooting.

Referring to the wiring diagram, remove fuse #22 in the cabin fuse panel. It's identified as being for the Air conditioner & Rear window defogger
relay coil, but it also powers the sub-fan relay. (See page 12-6 and 12-7 of the Owners Manual.) Turn the ignition to ON, and see if either fan is running.

If both fans do not run, then the problem is in the sub-fan control circuit. It could be a bad sub-fan relay (which can then be removed and tested) or a fault in the ECM.

If one of the fans runs (it would likely be the main fan), then also remove fuse #26. (It's identified as being for the Power window relay but also powers the Main fan relay #1 and #2). Again, turn the ignition to on and see if any fans run. If the single fan still runs, then the Main fan relay #1 or the ECM might be faulty.

If none run when fuse #26 is removed, then replace fuse #22 and see if the sub-fan runs.

Based on the results we can probably suggest further tests or determine the actual fault.
 

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I replaced 22 with 26 removed and neither fan is running. What does that mean?
 
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